Garment and fabric processing today includes dyeing and desizing. Sizing is important in the fabric weaving process. The size is usually removed in a finishing operation after the fabric is woven. In some fabrics e.g., denim, the size is left in to give desirable properties to the denim garment so as to improve the wear properties of the fabrics or garments. However, if the garments or fabrics are further processed, for example, treated with a crosslinking agent and/or decolorized or finished in garment form, it is necessary to first remove the sizing.
The removal of sizing is today performed in most textile operations by one or more of the following methods. The primary method of desizing is enzymatically, for example utilizing amylolytic enzymes. In garment finishing, this process is more costly. Mechanical action is another method of desizing. However, it is preferably used along with desizing by other methods. For example, abrasive drum linings in extractors and/or pumice stones are utilized to improve the garment softness, give the garment special features, etc. Alkaline and acidic hydrolysis have also been employed but such techniques can, depending upon the concentration employed also cause chemical attack of the fabric so as to result in a loss of the abrasive strength and wear resistance of the fabric. Oxidative desizing is generally employed using large concentrations of sodium hypochlorite in the desize solution. The use of hypochlorite creates environmental problems and further can significantly degrade the fabric. Desizing is required where the fabrics or garments are to undergo further processing such as dyeing, printing, decolorization, treatment with a crosslinker, ozone treatments and the like.
Garment dyeing technology, particularly with denim jeans where a differential color appearance is desirable, has focused on treatments in which the dyer starts with a dyed garment and achieves a differential color effect by partial color removal. Removal of color is achieved by use of porous stones soaked in oxidizing agents, such as strong bleach or permanganates, and more recently, by treatment with cellulase enzymes to remove fiber and thereby also remove some sizing and color.
The desizing and removal of color of denim garments generally requires two independent operations wherein the sizing is first removed and then the garment is treated chemically or physically to obtain removal of the color. It would be more economical and less time consuming if the two operations could be accomplished simultaneously. Such a procedure would be advantageous in garment treating processes wherein the garment undergoes a color fading procedure.
U.S. Pat. No. 5,118,322 to Wasinger et al, which is herein incorporated by reference, discloses an apparatus for practicing the present invention with oxidizing gases or vapors.
U.S. application Ser. No. 848,875 filed Mar. 10, 1992, now U.S. Pat. No. 5,313,911 issued May 24, 1994, which is herein incorporated by reference, discloses an apparatus which may be used together with the oxidizing gases of the invention.
It should be understood that the term "dye" as used herein is meant to include any of the materials which are used to provide a color to a fabric such as conventional dyes, pigments, or the like.
It should be understood that the term "reducing gas and steam" as used herein denotes a preferable method of the invention and is meant to include the reducing gas alone or the reducing gas diluted with inert gases.